1,4-dimethylbenzene

Definition

1,4-dimethylbenzene, also known as p-xylene, is an aromatic hydrocarbon compound with two methyl groups attached to a benzene ring in the para position. It is an important industrial chemical and a precursor for various organic compounds.

5 Must Know Facts For Your Next Test

1. The presence of two methyl groups in the para position on the benzene ring of 1,4-dimethylbenzene results in a symmetrical molecular structure.
2. 1,4-dimethylbenzene has a boiling point of 138°C and is a colorless, flammable liquid at room temperature.
3. It is used as a precursor in the production of terephthalic acid, which is a key building block for the manufacture of polyester plastics and fibers.
4. The 13C NMR spectrum of 1,4-dimethylbenzene displays six distinct signals, corresponding to the six unique carbon environments in the molecule.
5. The methyl carbon signals in the 13C NMR spectrum of 1,4-dimethylbenzene typically appear at around 21 ppm, while the aromatic carbon signals are observed between 125-135 ppm.

Review Questions

• Explain how the symmetrical structure of 1,4-dimethylbenzene affects its 13C NMR spectrum.
  • The symmetrical structure of 1,4-dimethylbenzene, with two methyl groups in the para position on the benzene ring, results in a simplified 13C NMR spectrum. The molecule has six unique carbon environments, leading to six distinct signals in the spectrum. The methyl carbon signals appear around 21 ppm, while the aromatic carbon signals are observed between 125-135 ppm. This symmetry in the molecular structure is reflected in the simplicity of the 13C NMR spectrum, making it easier to interpret and analyze.
• Describe the importance of 1,4-dimethylbenzene as an industrial chemical and its role in the production of other organic compounds.
  • 1,4-Dimethylbenzene, also known as p-xylene, is an important industrial chemical with a wide range of applications. It is primarily used as a precursor in the production of terephthalic acid, which is a key building block for the manufacture of polyester plastics and fibers. The symmetrical structure and reactivity of 1,4-dimethylbenzene make it a valuable starting material for the synthesis of various organic compounds, including those used in the production of plastics, textiles, and other materials. The versatility of 1,4-dimethylbenzene as an industrial chemical highlights its significance in the context of 13C NMR spectroscopy and its applications in organic chemistry.
• Analyze how the 13C NMR characteristics of 1,4-dimethylbenzene, such as the number and chemical shift of signals, can be used to identify and distinguish it from other xylene isomers.
  • The 13C NMR spectrum of 1,4-dimethylbenzene, with its six distinct signals, provides a unique fingerprint that can be used to identify and distinguish it from other xylene isomers, such as 1,2-dimethylbenzene (o-xylene) and 1,3-dimethylbenzene (m-xylene). The position of the methyl carbon signals around 21 ppm and the aromatic carbon signals between 125-135 ppm are characteristic of the para-substituted benzene ring structure. Additionally, the symmetry of the 1,4-dimethylbenzene molecule results in a simplified spectrum, making it easier to interpret and compare to other xylene isomers, which may have more complex 13C NMR profiles. This combination of structural information and spectral characteristics allows for the unambiguous identification of 1,4-dimethylbenzene in the context of 13C NMR spectroscopy.

Related terms

Aromatic Hydrocarbon: Aromatic hydrocarbons are a class of organic compounds characterized by the presence of one or more benzene rings in their structure.

Methyl Group: A methyl group is a functional group composed of a single carbon atom bonded to three hydrogen atoms, with the chemical formula -CH3.

Benzene Ring: A benzene ring is a cyclic structure composed of six carbon atoms with alternating single and double bonds, resulting in a stable, aromatic system.